How to Install Fiber Cement Siding

Installing fiber cement siding (FCS)—such as HardiePlank®—is easier than you might think, though there are some important differences from traditional wood siding. Installation instructions may vary depending on the manufacturer, and check with your local building inspector for any code requirements.

Safety First

Cutting FCS with a circular saw creates a large amount of dust which can lead to the incurable lung disease silicosis. Always cut siding outside and use a dust collecting saw hooked to a shop vac if possible.

Wear a NIOSH approved N-95 dust mask or respirator when cutting FCS.

Storage and Handling

Inspect siding carefully for damage when it arrives.

Store off the ground, making sure it is flat and well supported.

Keep it dry until it has been installed.

Carry pieces on edge to prevent breaking.

Support siding along its length when cutting.

Prep Work

Sheath walls with plywood, oriented strand board (OSB), or foam.

Cover sheathing with housewrap or felt paper.

Pop chalk lines to mark the location of studs.

Cutting Siding

Cutting fiber cement siding with a circular saw.

Circular Saw: While this is the most common method of cutting, it produces the most dust. Use a polycrystalline diamond toothed blade made for cutting FCS. Cut from the back side using a rafter square as a guide for right angle cuts. Several pieces may be stacked and cut at the same time.

Fiber Cement Shears: Special handheld electric shears can be used to make straight and curved cuts. An attachment called the TurboShear converts an electric drill into fiber cement shears. When using shears, cut with the back of the siding facing up.

Jigsaw: When fitted with a carbide coated blade, a jigsaw can be used to cut holes and curves. Cut from the back of the siding.

Scoring: Fiber cement siding can be scored and snapped like drywall, though the cuts are not very smooth. Score the face of the siding then pull up to break. A carbide tipped scoring knife lasts much longer than a standard utility knife blade.

Fastening Siding

Fiber cement siding can be nailed by hand or with a pneumatic nailer. It can also be attached using corrosion resistant screws.

Use hot-dipped galvanized or stainless steel nails.

Nails should penetrate through the sheathing and at least 1” into studs.

Position nails ¾” to 1” from the edge of the siding.

Siding can either be blind nailed at the top or face nailed at the bottom.

Use roofing nails for blind nailing and siding nails for face nailing.

Installing Trim

Putting up trim before installing fiber cement siding.

Begin by installing the inside and outside corners on the wall. These can be made from wood, vinyl, or thicker fiber cement products such as HardieTrim®. Corners should be at least ¼” thicker than two stacked pieces of siding to allow room for caulking.

Installing Siding

Fiber cement siding should be installed 6” or more above the grade level of the house with a 1”– 2” gap between horizontal surfaces like decks, steps, or adjacent roofs. Flash above doors and windows, leaving a ¼” gap between the flashing and siding. If you’re working alone, overlap gauges can be used to support the siding while you nail it.

Blind nailing fiber cement siding.

Begin by attaching a 1¼” wide strip of FCS 1/8” above the bottom of the first row to provide the proper angle for the siding. Next, nail the first row of siding into the studs, leaving 1/8” gaps at the corner boards to allow for caulking. Blind nailing is preferable to face nailing, since any nail heads are hidden by the next row of siding. Nails do not need to be predrilled except near the ends.

Center joints over studs unless special metal off stud joiners are used. Joints should be butted loosely together with a 4” wide strip of 30 pound felt positioned behind each one. Make sure the felt overhangs the previous row of siding to keep water from running behind it if the caulking fails.

Each row of siding should overlap by 1¼” or more. A spacer stick with a notch cut the length of the exposed part of the siding makes alignment easy.

Use a square or level to check that the rows line up at corners. When notching the siding around doors and windows, hold it in place and mark each end. To determine the depth of the notch, hook the spacer stick on the previous row of siding and measure from the top of the stick to the window or door unit.

When cutting angles on gables, start by cutting a piece of scrap siding or wood to the proper angle then use it to mark each piece. To measure the top row of siding on horizontal eaves, hook the spacer stick on the previous row and measure up to the eave, then rip the siding to width.

Finishing

Painting fiber cement siding.

While fiber cement siding should be painted as soon as possible after installation, factory primed FCS can go as long as six months without painting. Make sure it is clean and dry before painting. Caulk joints and ends first with a high quality latex caulking. Prime bare siding and any exposed cuts then topcoat with 100% acrylic latex paint.

I’m building a new home and have had HardiePlank lap siding installed. We live in South Carolina so it get pretty hot and we’re seeing the siding start to pull from the house where it was not face nailed. How concerned do we need to be? I understand due to the materials that it will contract and expand, but what would be acceptable? The pulling is visable from the ground looking up to the second floor, especially where the siding meets the trim.

i am trying to find a lap siding installation tool that clamps to the siding and spaces the reveeal evenly for eaach lap. this tool is adjustable for different reveals. i have used one in the past year but the carpenter to whom it belonged is i dont know where and i don’t know the name of the manufacturer. nifty little tool about two inches wide by about eight inches long by about one inch thick. can u help?

I am about to begin replacement of RB&B siding on my house with 8 1/4″ Hardiplank lap siding. I have been trying to locate the “flush” adapter tool used in conjunction with a pneumatic nail gun to prevent nails from being countersunk into the siding. Do you know where I might purchase this tool and its approximate cost?

Also, I’ve seen many comments about purchasing pre-primed siding. How much more expensive is this compared to unfinished siding? Which would you recommend?

Hi Jerry,
I not sure where to find the flush adaptor tool you mentioned. All of the Hardiplank siding comes preprimed. As far as buying it prepainted goes, the one person I know who installed it that way was pleased with the result.

Lots of helpful web-sites say to wash the siding before painting, but nobody says what is preferred to wash it with. Regular dish soap or laundry soap? Add a little bleach? Some special product at Lowes or Home Depot, or what? The Hardieplank site says nothing either, other than washing it.

Hi Allen,
We recommend mixing up a solution of TSP (trisodium phosphate) and water and scrubbing it down with that. If you have mildew problems, add some bleach to the mix (1 part bleach to 3-4 parts water) or use one of the products specifically made for killing mildew.

I’m having a problem figuring out what I need to do when going into a 90 degree angle on my house. I have ask a couple home improvement stores and I have gotten mixed answers. What is your answer because I’ve been going on all of your info when installing my siding.

Hi Bo,
As mentioned in the article above, there are inside and outside fiber cement corners available, or you could use lumber. Personally, I’d go with the fiber cement ones since they won’t expand and contract and would hold paint better. Good luck with your project!

Fiber cement destoried by mositure from furance exhaust steam. I know it wasn’t caulked correctly, but are there other things that need to be corrected? How far should the exhaust pipes stick out from the house and away from the siding to decrease moisture and heat to siding? Trane exhaust has a “cap” over inlet/ outlet pipes, is this okay? Any suggestions? HELP

Hi Randy,
The only way I know of to remove blind nailed fiber cement siding is to start at the top of the wall, cut through the caulking with a utility knife, use a flat prybar to carefully remove the nails, then take off each piece of siding. Since that would be a lot of work, you might consider surface mounting new outlets in waterproof boxes and running electrical wires to them from under the house. Good luck with your project.

We are building a 5 story building with Nichia Panels (cement Fibre ) and are attaching 1″ thick cement fibre) window trim over this siding . what would your recommendatio9n be for attaching the trim to the siding. The siding uses factory clips screwes thru to the 20 ga metal studs.?

Hi Adria,
It depends on the type of soffit material. If you are using wood, plywood, or fiber cement for the soffit, I would replace it before installing siding. Vinyl or aluminum soffit, on the other hand, is often applied after the siding has been completed. Good luck with your project!

Can you use James Hardie HardiePanel HZ10 96 in. Fiber Cement Siding on the inside?It looks really nice from the pictures and would have a nice cottage look to it for my 24’x24′ home im fixing to build.

ALWAYS wear dust protection for your lungs!!!! Stuff made me sick for 5 months, boss too. This is serious!!! Made a great looking house but I’m not working any more because of it. I can’t stress it enough, do not let the dust get in your lungs!

Danny:
I have a 2000 sq ft colonial covered in 12 year old vinyl siding with foam board underneath. Behind the foamboard is plywood, then 2X4’s spaced 1 ft apart. There is no insulation in the outer walls on the first floor, but insulation on the second floor. The house is in Connecticut. I am adding 1000 sq ft to the house and want to install cement fiber board. Can I install over the foam board? Do I need to wrap the house>? Should I insulate the bottom walls with blow in foam or is it not worth the cost due to minimal leakage with heat? Lastly, my vinyl siding on North side grows green moss/mold. I powerwash every year and comes off. Does it grow just a easy on smooth cement board and should I paid with mold resistent paint? Appreciate any help. Thanks and Regards Daren

I been wanting to renovate my home and use JH panels. I fould the Tamlyn Xtreme Trim reveal system on line that would help create a modern architectural lines. The website has james hardie logos on it and states that the procucts are recommended by J. Hardie. Has anyone used this trim or has any opinion on it?

i recently added the cement siding and finish my entire house. shortly after we had 3 days of winds over 75 mphs. A few of the lower pieces blew off and i was wonder if there is any other way to ensure this does happen again?

Our house is an old Hawaiian Plantation house built with single wall construction. No studs. The current particle board siding is made of some sort of compressed material that is starting to crumble apart. I want to replace it with HardiPlank. The problem is that the HardiPlank instructions state to use a 1.25” roofing nail. I tried some practice pieces and about 1/8 inch of the nail sticks through to the inside of the house. I would hate to have to grind down all those nails, plus I don’t think it would look very nice. Any chance I could get away with using 1” nails instead since all nails are going directly into the wood walls of the house. The current siding, which is heavier than HardiPlank is attached with 3/4” nails.

We built our home 8 yrs. ago; its a 1-1/2 story Colonial style, with dormers. We recently noticed that where the dormers protrude from the roof the cement board siding is deteriorating at the area where the siding butts up against the asphalt shingles. Should the siding butt against the shingles or should there have been some type of board or flashing used? We will have to tear off the cement board siding and replace it, and would like to know how to correctly remedy this.
We live in NW Ohio, and deal with snow that sits on the roof in these dormer areas.

Hi Bret,
As noted in our article above, a 1″ to 2″ gap should be left between the bottom of fiber cement siding and a roof. Click on the installation instruction link for your brand of siding at the bottom of the article to find out more. It might be possible to trim the existing siding back with a circular saw, if you’re careful not to cut through the flashing behind it. You would then need to prime and paint the bottom edges of the siding to prevent further deterioration. Good luck with your project!

On the Butt joints Hardi say not to chaulk just flash behind with 30 pound felt or step flashing. and caulk the end to joints only. reason why is hardi plank shrinks and the butt joints are staggered out you will notice it two to three years if you caulk the butt joints.

I too also live in Hawaii with a single wall redwood T&G siding, no studs. Planning on wrapping home with hardy plank but wanted to make sure using the short roofing nails (to prevent interior exposure, as my redwood thickness is measuring 5/8 and the hardy thickness is 5/16, total of 15/16 thickness) directly into the redwood wall will be sufficient. As John mentioned above, I plan on wrapping the exterior with tyvek homewrap and trimming off, then painting hardy plank and blind nailing a 7″ reveal. My exsisting redwood t&G siding is still in excellent shape and i have just finished scraping, sanding and priming with oil base primer. Your input on our fastener issue will be greatly appreciated as we are excited for the new look, protection and “double-wall effect” to our home!

I purchased my new home in South Carolina in November of 2010.The home had set not sold for about three years previous of our purchase due to the economic downturn. It has hardi plank siding on it and I am having problems with water coming in at some of the windows when it rains. There are joints in the siding above the windows that leak. I have inspected the joints and it appears that they were not caulked or it has fallen out due to contraction or expansion. Only the house wrap shows thru the joint. How do I repair this to prevent more water damage in the future. I am not a professional by no means but it appears that the siding was put on by unprofessional contractors

my son just bought a house that has had a stack of hardi plank siding on 4×4’s out on the patio for about 10 years. not covered. is it still any good to put up once it is laid out and allowed to dry? there is just about enough left to finish the house.

I have some 20 year old fiberboard siding on my home. I of it is in great shape with a few pieces with paint blistering. Can I add Hardiboard directly over the top of all of the fiberboard siding instead of removing the existing sideing? Reason to leave : added insulation, less mess, less cost. Any risks or disadvantages to this approach?

I purchased a new home with cement board external siding. The cement doard was face nailed and most of the nail heads are not flush. This is unsitely. I am concerned that the nails will rust and will deteriorate. The nails are resistant to being set. Attempt at setting resulted in damage to drywall inside the house. I have been told that there is glue on the nails that procludes removal or setting of the nails. Help???

I have been successful installing the cement siding directly on top of the existing masonite whenever the existing masonite siding is in fair shape with no rotting or wet boards or moisture trapped in the walls. Installation on top of the existing siding saves time, is less work, cleaner, and less costly.

Yes, a nail gun can be used. My personal opinion is there is no need to wrap the old siding. Just apply directly on top of the old wood plants. Make sure your nails are long enough. Cut the bottom siding plank to align with the bottom wood board so all of the siding overlaps. Enjoy the cost savings!!!

Take small pry bar containing flat end; gently pry loose good fiberboard sheet above the piece you want to replace(about one inch away from fiberboard that is to be removed) then use cutting tool to cut nails away so that new replacement board can be inserted to replace the rotten fiberboard. Nail and Caulk new board. Note: If you own a MultiMaster Cutting tool you can just cut out the rotten or damaged portion of the board you are replacing and insert the new piece instead of replacing an eight or twelve section of board. Enjoy the project!

My house was built with hariplank and the it was blind nailed. I recently saw a snake go up the side of my house and a lot of the boards are loose so I need to face nail th down. How do I hideyi the nail heads, will finishing nails work because they have a little head. Also I heard you should caulk each board. My contractor said the house needed to breathe but I also watch gecko’s go up under the boards. Please help!

our campground has 10′ x 10′ cabins with plywood walls covered on the outside with wood siding. The woodpeckers are KILLING us with all the holes. We want to put your cement fiber siding right on top of the wood siding. Is that ok? or
are we required to put a moisture barrier in between?

I recently addressed issues on a punch list for a building my company built. Much of it included poor exterior caulking and interior drywall damage. The exterior walls consist of Hardi Plank over exterior sheetrock on metal studs. The siding is screwed and I noticed sagging and waving. It seems odd that the siding is over drywall as there seems to be too much margin for play as drywall does not support sheer very well. Is this a good method or will I be constantly sent back to fix?

I bought a trailer and now im building a roof and taking the trailer in. I have framed the trailer walls with 2×4 on 16 inch center. my question can i attached cement siding stright to the 2×4 ? or do i need to put plywood up frist?

how can I replace just 12 inches of masonite siding with hardiplank lapsiding what do I need to do about the transition between the two?basically the siding is rotted on the bottom about twelve inches from the ground and the rest is good, the customer wants just the rotted siding replaced

SQUIRREL NO MORE! Want to keep squirrels from chewing their way into your home through the fiberboard or wood siding? Use the hardiplank (ONCE) to replace any damage from squirrels! Squirrels don’t like chewing on concrete!

I have several damaged HardiPlank cement “boards” that I would like to replace. All existing boards have been blind nailed. How can I remove the damaged boards without ruining the other siding that does not need to be replaced? Once the damaged boards are removed, how do I replace them with new ones, blind nailing them into place?

Hariplank is not squirrel impervious. I’ve got a friend whose house has dozens of feet of hardiplank with gnawed edges. The squirrels have also gnawed the plastic knobs on the gas grill. The Azek trim too has been molested with gnawing just off the deck. The house is in Fairfax Station, VA

I have a contractor who installed the cement fibre board, fiscia and trim boards with cut up lap siding. The corner trim boards are on top of the lap siding. I think he caulked over the butt seams of the lap siding. I also asked that the Brand Hardie be used and he did not. Do I have a case in getting it replaced or installed correctly?

We had cement board siding and skirting put on our brand new manufactured home in the San Diego area of CA. It is painted. I want to put a planting bed in front of the home for low water succulents. Since the home sits up so high, I want to make the bed a raised bed using a small rock wall to hold the soil. Can I mound the soil up against the cement board 6-8 inches high? There will not be a lot of moisture because the plants are low water succulents, but it will impede air flo to the cement board. If that is ill-advised, how can I achieve the desired effect? Can I layer plastic moisture barrier then cement board like in a shower or some other product?
Thanks, Patty

I have a contractor who installed the cement fibre board, fiscia and trim boards with cut up lap siding. The corner trim boards are on top of the lap siding. I think he caulked over the butt seams of the lap siding. I also asked that the Brand Hardie be used and he did not. Do I have a case in getting it replaced or installed correctly?

Sophia,
I have had vinyl and from what I’ve seen of the cement lap siding it is the winner hands down. The vinyl will fade, if it is anything but white and get brittle and get waves in it. That is why I have went to cement lap siding.
But this is my experience with vinyland the research on Hardie siding I have done. Look at the Hardie site. What a warranty! 30 years? I Hope this helps with your decision.
WalterAA

I’m going to be painting over hardy board as the homeowner has decided he doesn’t like the colour. Is it necessary to cover over nails prior to painting or can I just paint over them? I’m not sure if the installer used the blind nail method or not…..
Thanks!

i live in Texas and have vinyl siding on the back of my brick home (brick on 3 sides). We are looking to replace the back side with lap siding. do we need to remove the vinyl, or can we apply over the existing v siding?

I have a 70s home clad with corrugated fibre board (containing asbestos?) It is still in good condition however I want to clad over it with board and batten purely for aesthetics. Can I nail gun straight thru the board and the cement board into the stud? Or will it shatter? Thanks for any input.

We have purchased a new house and the outside exterior is covered with Hardi board.The house is only 7 months old and has just seen only this past summer as far as heat is concerned.Now there is a brown sticky liquid type material leaching out from under the Hardi board in different locations of the ouside of the house.It leaves quite a stain.What would cause this,we live in Toronto Ontario area of Canada.

Thanks for the great tips and for the very helpful step-by-step instructions! We decided to go with Hardie Plank and we are very happy with our decision. We were also looking for suggestions on how to properly wash our siding and what cleaning products to use – these are all wonderful ideas.

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